Maintenance - Siemens SCOR Installation, Operation & Maintenance Instructions Manual

5 Maintenance

5.1 General
Static devices require no preventive maintenance other than
a periodic operational test (see Page 20). If the relay fails to
function properly, contact Siemens Customer Service. When
returning the relay to the factory, ship the entire relay cradle
assembly, preferably in its case.
5.2 Storage
This protective relay contains aluminum electrolytic capacitors
which generally have a storage life expectancy in excess of ten
years at storage temperatures less than 40° C. Typically, the life
expectancy of the capacitor is cut in half for every
temperature. Storage life can be extended if, at one-year inter­
vals, power is applied to the relay for a period of 30 minutes.
5.3 Timekeeping
The real-time clock within the relay, once set by the Power
Monitor unit after power up, maintains time to a resolution of 0.01
second ; however, drift within the clock can be as much as 0.5
seconds per day. In order to keep all of the clocks in the system
in proper synchronization, the Power Monitor periodically broad­
casts the correct time.
Note that changing the time within a relay by seconds or minutes
can upset instrumentation functions such as demand calcula­
tions.
1 oo
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